An animated mine that will be duplicated 30-50 times to mimic a mine field.

All of that along with the players ship thrusters, lasers (bullets) for all on screen ships and small explosions each time a bullet hits a ship, plus larger explosions for when the ships health runs out and explodes.

In a very basic sense, everything boils down to object count for the cpu. Animations are objects, particles are objects. It looks like your phone is starting to struggle with 10k objects, although 40+ fps is still rather passable. So try to avoid going over that.